Within typical electronic devices, multiple integrated circuits and other electronic components are mounted to and are interconnected by one or more Printed Circuit Boards (PCBs). The integrated circuits and electronic components are typically solder-mounted to the PCB such that signal conductors of a PCB form individual electrical connections between selected terminals of the integrated circuits and selected terminals of the other components. The signal conductors are disposed on one or more insulative substrate layers of a material such as FR4 glass reinforced epoxy laminate fiberglass. In some applications, however, finer geometry signal conductors are needed. In such applications, the fine geometry lithography and semiconductor processing technology used to fabricate integrated circuits is employed to make a substrate having fine geometry signal conductors. In some cases, structures referred to as Through Silicon Vias (TSV) extend all the way through the substrate so that electrical connections can be made from one major planar side of the substrate, perpendicularly through the substrate, and to the opposite major planar side of the substrate. A Silicon Circuit Board (SiCB) and an interposer are examples of two such substrate structures that may involve TSVs and fine geometry signal conductors. Methods and structures for improving such substrate structures are sought.